/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.tomcat.util.modeler;

import org.apache.juli.logging.Log;
import org.apache.juli.logging.LogFactory;
import org.apache.tomcat.util.modeler.modules.ModelerSource;

import javax.management.*;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.lang.management.ManagementFactory;
import java.net.URL;
import java.util.*;

/*
   Issues:
   - exceptions - too many "throws Exception"
   - double check the interfaces 
   - start removing the use of the experimental methods in tomcat, then remove
     the methods ( before 1.1 final )
   - is the security enough to prevent Registry being used to avoid the permission
    checks in the mbean server ?
*/

/**
 * Registry for modeler MBeans.
 * <p>
 * This is the main entry point into modeler. It provides methods to create
 * and manipulate model mbeans and simplify their use.
 * <p>
 * Starting with version 1.1, this is no longer a singleton and the static
 * methods are strongly deprecated. In a container environment we can expect
 * different applications to use different registries.
 * <p>
 * This class is itself an mbean.
 * <p>
 * IMPORTANT: public methods not marked with @since x.x are experimental or
 * internal. Should not be used.
 *
 * @author Craig R. McClanahan
 * @author Costin Manolache
 */
public class Registry implements RegistryMBean, MBeanRegistration {
	/**
	 * The Log instance to which we will write our log messages.
	 */
	private static final Log log = LogFactory.getLog(Registry.class);

	// Support for the factory methods

	/**
	 * Will be used to isolate different apps and enhance security.
	 */
	private static HashMap<Object, Registry> perLoaderRegistries = null;

	/**
	 * The registry instance created by our factory method the first time
	 * it is called.
	 */
	private static Registry registry = null;

	// Per registry fields

	/**
	 * The <code>MBeanServer</code> instance that we will use to register
	 * management beans.
	 */
	private MBeanServer server = null;

	/**
	 * The set of ManagedBean instances for the beans this registry
	 * knows about, keyed by name.
	 */
	private HashMap<String, ManagedBean> descriptors =
			new HashMap<String, ManagedBean>();

	/**
	 * List of managed beans, keyed by class name
	 */
	private HashMap<String, ManagedBean> descriptorsByClass =
			new HashMap<String, ManagedBean>();

	// map to avoid duplicated searching or loading descriptors
	private HashMap<String, URL> searchedPaths = new HashMap<String, URL>();

	private Object guard;

	// Id - small ints to use array access. No reset on stop()
	// Used for notifications
	private Hashtable<String, Hashtable<String, Integer>> idDomains =
			new Hashtable<String, Hashtable<String, Integer>>();
	private Hashtable<String, int[]> ids = new Hashtable<String, int[]>();


	// ----------------------------------------------------------- Constructors

	/**
	 */
	public Registry() {
		super();
	}

	// -------------------- Static methods  --------------------
	// Factories

	/**
	 * Factory method to create (if necessary) and return our
	 * <code>Registry</code> instance.
	 * <p>
	 * Use this method to obtain a Registry - all other static methods
	 * are deprecated and shouldn't be used.
	 * <p>
	 * The current version uses a static - future versions could use
	 * the thread class loader.
	 *
	 * @param key   Support for application isolation. If null, the context class
	 *              loader will be used ( if setUseContextClassLoader is called ) or the
	 *              default registry is returned.
	 * @param guard Prevent access to the registry by untrusted components
	 * @since 1.1
	 */
	public static synchronized Registry getRegistry(Object key, Object guard) {
		Registry localRegistry;
		if (perLoaderRegistries != null) {
			if (key == null)
				key = Thread.currentThread().getContextClassLoader();
			if (key != null) {
				localRegistry = perLoaderRegistries.get(key);
				if (localRegistry == null) {
					localRegistry = new Registry();
//                    localRegistry.key=key;
					localRegistry.guard = guard;
					perLoaderRegistries.put(key, localRegistry);
					return localRegistry;
				}
				if (localRegistry.guard != null &&
						localRegistry.guard != guard) {
					return null; // XXX Should I throw a permission ex ?
				}
				return localRegistry;
			}
		}

		// static
		if (registry == null) {
			registry = new Registry();
		}
		if (registry.guard != null &&
				registry.guard != guard) {
			return null;
		}
		return (registry);
	}

	/**
	 * Allow containers to isolate apps. Can be called only once.
	 * It  is highly recommended you call this method if using Registry in
	 * a container environment. The default is false for backward compatibility
	 *
	 * @param enable
	 * @since 1.1
	 */
	public static void setUseContextClassLoader(boolean enable) {
		if (enable) {
			perLoaderRegistries = new HashMap<Object, Registry>();
		}
	}

	// -------------------- Generic methods  --------------------

	/**
	 * Lifecycle method - clean up the registry metadata.
	 * Called from resetMetadata().
	 *
	 * @since 1.1
	 */
	@Override
	public void stop() {
		descriptorsByClass = new HashMap<String, ManagedBean>();
		descriptors = new HashMap<String, ManagedBean>();
		searchedPaths = new HashMap<String, URL>();
	}

	/**
	 * Load an extended mlet file. The source can be an URL, File or
	 * InputStream.
	 * <p>
	 * All mbeans will be instantiated, registered and the attributes will be
	 * set. The result is a list of ObjectNames.
	 *
	 * @param source InputStream or URL of the file
	 * @param cl     ClassLoader to be used to load the mbeans, or null to use the
	 *               default JMX mechanism ( i.e. all registered loaders )
	 * @return List of ObjectName for the loaded mbeans
	 * @throws Exception
	 * @since 1.1
	 */
	@Override
	public List<ObjectName> loadMBeans(Object source, ClassLoader cl)
			throws Exception {
		return load("MbeansSource", source, null);
	}

	/**
	 * Load descriptors. The source can be a File or URL or InputStream for the
	 * descriptors file. In the case of File and URL, if the extension is ".ser"
	 * a serialized version will be loaded.
	 * <p>
	 * This method should be used to explicitly load metadata - but this is not
	 * required in most cases. The registerComponent() method will find metadata
	 * in the same package.
	 *
	 * @param source
	 */
	@Override
	public void loadMetadata(Object source) throws Exception {
		loadDescriptors(null, source, null);
	}

	/**
	 * Register a bean by creating a modeler mbean and adding it to the
	 * MBeanServer.
	 * <p>
	 * If metadata is not loaded, we'll look up and read a file named
	 * "mbeans-descriptors.ser" or "mbeans-descriptors.xml" in the same package
	 * or parent.
	 * <p>
	 * If the bean is an instance of DynamicMBean. it's metadata will be converted
	 * to a model mbean and we'll wrap it - so modeler services will be supported
	 * <p>
	 * If the metadata is still not found, introspection will be used to extract
	 * it automatically.
	 * <p>
	 * If an mbean is already registered under this name, it'll be first
	 * unregistered.
	 * <p>
	 * If the component implements MBeanRegistration, the methods will be called.
	 * If the method has a method "setRegistry" that takes a RegistryMBean as
	 * parameter, it'll be called with the current registry.
	 *
	 * @param bean  Object to be registered
	 * @param oname Name used for registration
	 * @param type  The type of the mbean, as declared in mbeans-descriptors. If
	 *              null, the name of the class will be used. This can be used as a hint or
	 *              by subclasses.
	 * @since 1.1
	 */
	@Override
	public void registerComponent(Object bean, String oname, String type)
			throws Exception {
		registerComponent(bean, new ObjectName(oname), type);
	}

	/**
	 * Unregister a component. We'll first check if it is registered,
	 * and mask all errors. This is mostly a helper.
	 *
	 * @param oname
	 * @since 1.1
	 */
	@Override
	public void unregisterComponent(String oname) {
		try {
			unregisterComponent(new ObjectName(oname));
		} catch (MalformedObjectNameException e) {
			log.info("Error creating object name " + e);
		}
	}

	/**
	 * Invoke a operation on a list of mbeans. Can be used to implement
	 * lifecycle operations.
	 *
	 * @param mbeans    list of ObjectName on which we'll invoke the operations
	 * @param operation Name of the operation ( init, start, stop, etc)
	 * @param failFirst If false, exceptions will be ignored
	 * @throws Exception
	 * @since 1.1
	 */
	@Override
	public void invoke(List<ObjectName> mbeans, String operation,
	                   boolean failFirst) throws Exception {
		if (mbeans == null) {
			return;
		}
		Iterator<ObjectName> itr = mbeans.iterator();
		while (itr.hasNext()) {
			ObjectName current = itr.next();
			try {
				if (current == null) {
					continue;
				}
				if (getMethodInfo(current, operation) == null) {
					continue;
				}
				getMBeanServer().invoke(current, operation,
						new Object[]{}, new String[]{});

			} catch (Exception t) {
				if (failFirst) throw t;
				log.info("Error initializing " + current + " " + t.toString());
			}
		}
	}

	// -------------------- ID registry --------------------

	/**
	 * Return an int ID for faster access. Will be used for notifications
	 * and for other operations we want to optimize.
	 *
	 * @param domain Namespace
	 * @param name   Type of the notification
	 * @return An unique id for the domain:name combination
	 * @since 1.1
	 */
	@Override
	public synchronized int getId(String domain, String name) {
		if (domain == null) {
			domain = "";
		}
		Hashtable<String, Integer> domainTable = idDomains.get(domain);
		if (domainTable == null) {
			domainTable = new Hashtable<String, Integer>();
			idDomains.put(domain, domainTable);
		}
		if (name == null) {
			name = "";
		}
		Integer i = domainTable.get(name);

		if (i != null) {
			return i.intValue();
		}

		int id[] = ids.get(domain);
		if (id == null) {
			id = new int[1];
			ids.put(domain, id);
		}
		int code = id[0]++;
		domainTable.put(name, Integer.valueOf(code));
		return code;
	}

	// -------------------- Metadata   --------------------
	// methods from 1.0

	/**
	 * Add a new bean metadata to the set of beans known to this registry.
	 * This is used by internal components.
	 *
	 * @param bean The managed bean to be added
	 * @since 1.0
	 */
	public void addManagedBean(ManagedBean bean) {
		// XXX Use group + name
		descriptors.put(bean.getName(), bean);
		if (bean.getType() != null) {
			descriptorsByClass.put(bean.getType(), bean);
		}
	}

	/**
	 * Find and return the managed bean definition for the specified
	 * bean name, if any; otherwise return <code>null</code>.
	 *
	 * @param name Name of the managed bean to be returned. Since 1.1, both
	 *             short names or the full name of the class can be used.
	 * @since 1.0
	 */
	public ManagedBean findManagedBean(String name) {
		// XXX Group ?? Use Group + Type
		ManagedBean mb = descriptors.get(name);
		if (mb == null)
			mb = descriptorsByClass.get(name);
		return mb;
	}

	/**
	 * Return the set of bean names for all managed beans known to
	 * this registry.
	 *
	 * @since 1.0
	 */
	public String[] findManagedBeans() {
		return descriptors.keySet().toArray(new String[0]);
	}

	/**
	 * Return the set of bean names for all managed beans known to
	 * this registry that belong to the specified group.
	 *
	 * @param group Name of the group of interest, or <code>null</code>
	 *              to select beans that do <em>not</em> belong to a group
	 * @since 1.0
	 */
	public String[] findManagedBeans(String group) {

		ArrayList<String> results = new ArrayList<String>();
		Iterator<ManagedBean> items = descriptors.values().iterator();
		while (items.hasNext()) {
			ManagedBean item = items.next();
			if ((group == null)) {
				if (item.getGroup() == null) {
					results.add(item.getName());
				}
			} else if (group.equals(item.getGroup())) {
				results.add(item.getName());
			}
		}
		String values[] = new String[results.size()];
		return results.toArray(values);

	}

	/**
	 * Remove an existing bean from the set of beans known to this registry.
	 *
	 * @param bean The managed bean to be removed
	 * @since 1.0
	 */
	public void removeManagedBean(ManagedBean bean) {
		// TODO: change this to use group/name
		descriptors.remove(bean.getName());
		descriptorsByClass.remove(bean.getType());
	}

	// -------------------- Helpers  --------------------

	/**
	 * Get the type of an attribute of the object, from the metadata.
	 *
	 * @param oname
	 * @param attName
	 * @return null if metadata about the attribute is not found
	 * @since 1.1
	 */
	public String getType(ObjectName oname, String attName) {
		String type = null;
		MBeanInfo info = null;
		try {
			info = server.getMBeanInfo(oname);
		} catch (Exception e) {
			log.info("Can't find metadata for object" + oname);
			return null;
		}

		MBeanAttributeInfo attInfo[] = info.getAttributes();
		for (int i = 0; i < attInfo.length; i++) {
			if (attName.equals(attInfo[i].getName())) {
				type = attInfo[i].getType();
				return type;
			}
		}
		return null;
	}

	/**
	 * Find the operation info for a method
	 *
	 * @param oname
	 * @param opName
	 * @return the operation info for the specified operation
	 */
	public MBeanOperationInfo getMethodInfo(ObjectName oname, String opName) {
		MBeanInfo info = null;
		try {
			info = server.getMBeanInfo(oname);
		} catch (Exception e) {
			log.info("Can't find metadata " + oname);
			return null;
		}
		MBeanOperationInfo attInfo[] = info.getOperations();
		for (int i = 0; i < attInfo.length; i++) {
			if (opName.equals(attInfo[i].getName())) {
				return attInfo[i];
			}
		}
		return null;
	}

	/**
	 * Unregister a component. This is just a helper that
	 * avoids exceptions by checking if the mbean is already registered
	 *
	 * @param oname
	 */
	public void unregisterComponent(ObjectName oname) {
		try {
			if (getMBeanServer().isRegistered(oname)) {
				getMBeanServer().unregisterMBean(oname);
			}
		} catch (Throwable t) {
			log.error("Error unregistering mbean ", t);
		}
	}

	/**
	 * Factory method to create (if necessary) and return our
	 * <code>MBeanServer</code> instance.
	 */
	public synchronized MBeanServer getMBeanServer() {
		long t1 = System.currentTimeMillis();

		if (server == null) {
			if (MBeanServerFactory.findMBeanServer(null).size() > 0) {
				server = MBeanServerFactory.findMBeanServer(null).get(0);
				if (log.isDebugEnabled()) {
					log.debug("Using existing MBeanServer " + (System.currentTimeMillis() - t1));
				}
			} else {
				server = ManagementFactory.getPlatformMBeanServer();
				if (log.isDebugEnabled()) {
					log.debug("Creating MBeanServer" + (System.currentTimeMillis() - t1));
				}
			}
		}
		return (server);
	}

	/**
	 * Set the <code>MBeanServer</code> to be utilized for our
	 * registered management beans.
	 *
	 * @param server The new <code>MBeanServer</code> instance
	 */
	public void setMBeanServer(MBeanServer server) {
		this.server = server;
	}

	/**
	 * Find or load metadata.
	 */
	public ManagedBean findManagedBean(Object bean, Class<?> beanClass,
	                                   String type) throws Exception {
		if (bean != null && beanClass == null) {
			beanClass = bean.getClass();
		}

		if (type == null) {
			type = beanClass.getName();
		}

		// first look for existing descriptor
		ManagedBean managed = findManagedBean(type);

		// Search for a descriptor in the same package
		if (managed == null) {
			// check package and parent packages
			if (log.isDebugEnabled()) {
				log.debug("Looking for descriptor ");
			}
			findDescriptor(beanClass, type);

			managed = findManagedBean(type);
		}

		// Still not found - use introspection
		if (managed == null) {
			if (log.isDebugEnabled()) {
				log.debug("Introspecting ");
			}

			// introspection
			loadDescriptors("MbeansDescriptorsIntrospectionSource",
					beanClass, type);

			managed = findManagedBean(type);
			if (managed == null) {
				log.warn("No metadata found for " + type);
				return null;
			}
			managed.setName(type);
			addManagedBean(managed);
		}
		return managed;
	}

	/**
	 * EXPERIMENTAL Convert a string to object, based on type. Used by several
	 * components. We could provide some pluggability. It is here to keep
	 * things consistent and avoid duplication in other tasks
	 *
	 * @param type  Fully qualified class name of the resulting value
	 * @param value String value to be converted
	 * @return Converted value
	 */
	public Object convertValue(String type, String value) {
		Object objValue = value;

		if (type == null || "java.lang.String".equals(type)) {
			// string is default
			objValue = value;
		} else if ("javax.management.ObjectName".equals(type) ||
				"ObjectName".equals(type)) {
			try {
				objValue = new ObjectName(value);
			} catch (MalformedObjectNameException e) {
				return null;
			}
		} else if ("java.lang.Integer".equals(type) ||
				"int".equals(type)) {
			objValue = Integer.valueOf(value);
		} else if ("java.lang.Long".equals(type) ||
				"long".equals(type)) {
			objValue = Long.valueOf(value);
		} else if ("java.lang.Boolean".equals(type) ||
				"boolean".equals(type)) {
			objValue = Boolean.valueOf(value);
		}
		return objValue;
	}

	/**
	 * Experimental.
	 *
	 * @param sourceType
	 * @param source
	 * @param param
	 * @return List of descriptors
	 * @throws Exception
	 */
	public List<ObjectName> load(String sourceType, Object source,
	                             String param) throws Exception {
		if (log.isTraceEnabled()) {
			log.trace("load " + source);
		}
		String location = null;
		String type = null;
		Object inputsource = null;

		if (source instanceof URL) {
			URL url = (URL) source;
			location = url.toString();
			type = param;
			inputsource = url.openStream();
			if (sourceType == null) {
				sourceType = sourceTypeFromExt(location);
			}
		} else if (source instanceof File) {
			location = ((File) source).getAbsolutePath();
			inputsource = new FileInputStream((File) source);
			type = param;
			if (sourceType == null) {
				sourceType = sourceTypeFromExt(location);
			}
		} else if (source instanceof InputStream) {
			type = param;
			inputsource = source;
		} else if (source instanceof Class<?>) {
			location = ((Class<?>) source).getName();
			type = param;
			inputsource = source;
			if (sourceType == null) {
				sourceType = "MbeansDescriptorsIntrospectionSource";
			}
		}

		if (sourceType == null) {
			sourceType = "MbeansDescriptorsDigesterSource";
		}
		ModelerSource ds = getModelerSource(sourceType);
		List<ObjectName> mbeans =
				ds.loadDescriptors(this, type, inputsource);

		return mbeans;
	}

	private String sourceTypeFromExt(String s) {
		if (s.endsWith(".ser")) {
			return "MbeansDescriptorsSerSource";
		} else if (s.endsWith(".xml")) {
			return "MbeansDescriptorsDigesterSource";
		}
		return null;
	}

	/**
	 * Register a component
	 * XXX make it private
	 *
	 * @param bean
	 * @param oname
	 * @param type
	 * @throws Exception
	 */
	public void registerComponent(Object bean, ObjectName oname, String type)
			throws Exception {
		if (log.isDebugEnabled()) {
			log.debug("Managed= " + oname);
		}

		if (bean == null) {
			log.error("Null component " + oname);
			return;
		}

		try {
			if (type == null) {
				type = bean.getClass().getName();
			}

			ManagedBean managed = findManagedBean(bean.getClass(), type);

			// The real mbean is created and registered
			DynamicMBean mbean = managed.createMBean(bean);

			if (getMBeanServer().isRegistered(oname)) {
				if (log.isDebugEnabled()) {
					log.debug("Unregistering existing component " + oname);
				}
				getMBeanServer().unregisterMBean(oname);
			}

			getMBeanServer().registerMBean(mbean, oname);
		} catch (Exception ex) {
			log.error("Error registering " + oname, ex);
			throw ex;
		}
	}

	/**
	 * Lookup the component descriptor in the package and
	 * in the parent packages.
	 *
	 * @param packageName
	 */
	public void loadDescriptors(String packageName, ClassLoader classLoader) {
		String res = packageName.replace('.', '/');

		if (log.isTraceEnabled()) {
			log.trace("Finding descriptor " + res);
		}

		if (searchedPaths.get(packageName) != null) {
			return;
		}
		String descriptors = res + "/mbeans-descriptors.ser";

		URL dURL = classLoader.getResource(descriptors);

		if (dURL == null) {
			descriptors = res + "/mbeans-descriptors.xml";
			dURL = classLoader.getResource(descriptors);
		}
		if (dURL == null) {
			return;
		}

		log.debug("Found " + dURL);
		searchedPaths.put(packageName, dURL);
		try {
			if (descriptors.endsWith(".xml"))
				loadDescriptors("MbeansDescriptorsDigesterSource", dURL, null);
			else
				loadDescriptors("MbeansDescriptorsSerSource", dURL, null);
			return;
		} catch (Exception ex) {
			log.error("Error loading " + dURL);
		}

		return;
	}

	/**
	 * @param sourceType
	 * @param source
	 * @param param
	 * @throws Exception
	 */
	private void loadDescriptors(String sourceType, Object source,
	                             String param) throws Exception {
		load(sourceType, source, param);
	}

	/**
	 * Lookup the component descriptor in the package and
	 * in the parent packages.
	 *
	 * @param beanClass
	 * @param type
	 */
	private void findDescriptor(Class<?> beanClass, String type) {
		if (type == null) {
			type = beanClass.getName();
		}
		ClassLoader classLoader = null;
		if (beanClass != null) {
			classLoader = beanClass.getClassLoader();
		}
		if (classLoader == null) {
			classLoader = Thread.currentThread().getContextClassLoader();
		}
		if (classLoader == null) {
			classLoader = this.getClass().getClassLoader();
		}

		String className = type;
		String pkg = className;
		while (pkg.indexOf(".") > 0) {
			int lastComp = pkg.lastIndexOf(".");
			if (lastComp <= 0) return;
			pkg = pkg.substring(0, lastComp);
			if (searchedPaths.get(pkg) != null) {
				return;
			}
			loadDescriptors(pkg, classLoader);
		}
		return;
	}


	// -------------------- Registration  --------------------

	private ModelerSource getModelerSource(String type)
			throws Exception {
		if (type == null) type = "MbeansDescriptorsDigesterSource";
		if (type.indexOf(".") < 0) {
			type = "org.apache.tomcat.util.modeler.modules." + type;
		}

		Class<?> c = Class.forName(type);
		ModelerSource ds = (ModelerSource) c.newInstance();
		return ds;
	}

	@Override
	public ObjectName preRegister(MBeanServer server,
	                              ObjectName name) throws Exception {
		this.server = server;
		return name;
	}

	@Override
	public void postRegister(Boolean registrationDone) {
	}

	@Override
	public void preDeregister() throws Exception {
	}


	// -------------------- DEPRECATED METHODS  --------------------
	// May still be used in tomcat
	// Never part of an official release

	@Override
	public void postDeregister() {
	}

	/**
	 * @deprecated
	 */
	@Deprecated
	public ManagedBean findManagedBean(Class<?> beanClass, String type)
			throws Exception {
		return findManagedBean(null, beanClass, type);
	}

	public void resetMetadata() {
		stop();
	}

}
